Ultrasound Assessment of Irrigation Fluid Effect on Extravascular Lung Water in Patients Undergoing Percutaneous Nephrolithotomy

Study protocol:

Anesthetic technique:- After adequate pre-oxygenation for 3-5 min, General anesthesia will be induced by intravenous lidocaine 60 mg, propofol (2mg/kg) and cis-atracurium (0.15 mg/ kg) to facilitate endotracheal intubation by a cuffed endotracheal tube (size 6.5-7.5-mm), then the patient will be connected to mechanical ventilation which will be maintained with an 8 ml/ kg tidal volume, and ventilation frequency well be adjusted to maintain end-tidal CO2 between 30-35 mmHg. Anesthesia will be maintained with isoflurane (0.8-1.0%) in a mixture of oxygen and air (50:50%) and cis-atracurium (0.03 mg/ kg) and maintained every 20 min. Standard monitoring will be used intraoperatively including non-invasive arterial blood pressure, electrocardiography, end-tidal CO2, peripheral oxygen saturation and esophageal core temperature. Patients will receive one liter of normal saline infused over the first 2 hours intraoperatively as their fasting requirements and will be infused with 3 ml/kg/hour of Ringer's acetate as a maintenance fluid. Intraoperative hypotension (more than 20% decrease of the baseline of the patient ) will be treated by a bolus dose of crystalloid (4 ml/kg) as well as a bolus dose of ephedrine (3 mg). Atropine (0.5 mg) will be used to treat bradycardia if the heart rate is <60 beat/min. At end of surgery, isoflurane will be discontinued, and neuromuscular block will be antagonized using neostigmine (0.05 mg/kg) and atropine (0.02 mg/kg), intravenous paracetamol will be given as analgesia and boluses of fentanil Intraoperative as needed . Extubation will performed when patients began breathing spontaneously and were able to respond to verbal requests and discharge to post-Anesthesia Care Unit (PACU) but if the patient is not fulfilling criteria of extubation so discharge will be to Intensive care unit (ICU). If acute Postoperative lung congestion occurs with postoperative hypoxemia and desaturation, it will be treated with furosemide.

Blood samples will be collected for CBC, ABG and electrolytes as sodium and potassium Pre-operative, intraoperative and Immediately Post-operative.

Lung ultrasound scan technique: -

Each patient will be assessed for the presence of B-lines before induction of anesthesia and after end of anesthesia. A curved 2-6-MHz probe of Mindray machine will be used to do a series of scans with the patient in the supine position by applying the probe perpendicular to the skin over intercostal spaces along anatomical reference lines. More precisely, we will scan the anterolateral hemithoraxes along the parasternal, midclavicular, anterior axillary and mid-axillary lines. The left hemithorax will be scanned from the second to the fourth intercostal space, whereas the right lung will be scanned from the second to the fifth intercostal space, giving a total of 28 scanning sites. The edematous lung shows B-lines as vertical narrow bands originating from the pleural line and extending to the bottom of the image. A B-line score of ≤5 will be considered a normal sonographic pattern, since a few B-lines can be present in healthy subjects, especially above the diaphragm.